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'S OF CHANGES OF BIRTH AND DEATH RATES
age-specific rates of 1966, low though they were, the American popu-would replace itself even if all childbearing ceased at age 35. As we :e, other countries are moving toward this pattern of limiting child-; to the younger ages.
of Change in Death Rates on Replacement
definition of RQ shows the effect on replacement of a decrease in the rate at age 0 to 4. When 5Af0 goes down by A57W0, every subsequent ill go up in the ratio e5 AsMo. Hence the Net Reproduction Rate will in the ratio e5AsMo. The proportional increase in RQ will be about p the absolute increase 5RQ&.5M0. This is very nearly the same as the on R0 of an increase in all of the Fx simultaneously. It matters little Jacement whether mortality of infants and young children declines or y increases.
effect on RQ of a fall in the death rates SM5 or 5M10 is about the s in SM0. But for ages x beyond 15 the fall &SMX only affects part of iroductive life of women, a part that diminishes with increase in the age e fall.
hange of death rate at age 55 to 59 or higher has no effect on replace-This clashes with intuition: if the death rate goes down and people live , will not the population increase more rapidly? The answer is that the in effect of an improvement at age 55 to 59 is to raise the level of the ttion curve but not its long-run rate of increase. A stylized expression difference is to be seen in Figure 1. For purposes of the chart the ;e in population has been placed in a step at the moment of its occur-though in fact it will be smoother and spread over more time. The
jr of people * ions, all ages er
Effect of change in 5M0
Effect of change in 5M55
Geometric increase if no change in ratesages requires an investigation of how the Net and Gross Reproduction Rates would respond to changes in birth and death rates. The GRR is simpler: it is unaffected by mortality, and a change in an age-specific fertility rate will make an equal change in the GRR. The United States had a GRR of 1.336 in 1966; the average woman who lives through the child-bearing period has approximately 1.336 girls, and about 1.049 times as many boys, or about 2.736 children altogether, at the rates of 1966. Disregarding differences in fertility of those few women who die before the end of their childbearing period, this is the average completed family implied by 1966 age-specific rates. The rate of childbearing to women of 35 to 39 was 0.0206, among the lowest in the world. American women prefer to bear their children early; they bear enough children before age 35 to provide a Gross Reproduction Rate and even a Net Reproduction Rate of more than unity.ife or lives saved may be supposed the result of a durable improvement in medical technique, then we want to know the effect on populations of theage by 2.42 years in comparison with Sweden 1800—evidently the survivorship of Honduras was espe-ion Change on the Attainment of Educa-bout 20 percent. For the less developedHilton Salhanick has observed that some women practicing the rhythm method will break or lose their thermometers at the critical juncture in theirright, therefore alwayshas some c